The present invention has particular utility in connection with those oil tanks used for storing crude oil as it is pumped from the ground. Such tanks are typically between three and four meters in diameter and six meters high and contain about 400, 500, or 1,000 barrels of oil. The conditions of use are often quite rugged. It is therefore important that any level gauge for such a tank be itself rugged and reliable.
In response to these requirements, there has been developed a level indicating system consisting of a float inside the tank connected to one end of a cable that runs up to the top of the tank, over a pulley and down to a weight on the outside. The weight conventionally runs in a vertical track on the side of the tank, with the position of the weight indicating the oil level in the tank. This system is not always satisfactory as the weight will often stick in the track in which it runs so that in order to determine the actual level of liquid, it is necessary for an operator to go to the tank, pull on the weight and set the system oscillating so that when the oscillations damp down, the reading is fairly reliable.
The present invention proposes an alternative system that is more reliable, eliminates the sticking of the weight in the track, and where necessary can be read from a remote location.